An investigation into the anthelmintic properties of seed extracts from endophyte containing pasture grasses

Abstract

The study investigated the in vitro anthelmintic properties of extracts from seeds containing the endophytes AR1, AR37, wild type in perennial rye grass (RG), and the loline producing endophytes namely Meadow Fescue (MF and U2) and Tall Fescue (TF and AR542) with Nil endophytes rye grass (Nil RG) and Nil endophytes tall fescue (Nil TF) used as controls. The in vitro efficacy of the extracts was determined on the gastro-intestinal parasite species Teladorsagia circumcincta and Trichostrongylus colubriformis. For loline producing endophytes, the LD50 for T. colubriformis egg hatching for AR542 and Nil TF were not different from each other (P>0.05) but significantly differed from meadow fescue (P<0.05). Within the rye grass varieties, the LD50 for T. circumcincta egg hatching for AR1 and wild-type endophyte were not different from each other (P>0.05) but differed significantly from AR37 and Nil RG (P<0.05). For T. circumcincta larvae incubated in loline producing endophytes, there was no observable difference in the immobility of larvae incubated in either AR542, nil Tall fescue or meadow fescue (P>0.05). For rye grass varieties, LD50 for larval immobility was significantly greater in nil RG and wild-type RG than either AR1 or AR37. For T. colubriformis larvae incubated in loline producing endophytes, there was no observable difference in the immobility of larvae incubated in either AR542 or nil Tall fescue but differed from meadow fescue (P>0.05). For rye grass varieties, LD50 for larval immobility was significantly greater in Nil RG compared with AR1, AR37 and wild-type endophyte and AR1 and AR37 were significantly greater than wild-type endophyte. Re-dilution significantly reduced the percentage of immobile T. circumcincta L3 from 59% at 15hrs to 24% (P<0.001) and significantly reduced the percentage of immobile T. colubriformis L3 from 63% at 15hrs to 39% (P<0.001) indicating that effects were reversible. In conclusion, the apparent anthelmintic properties demonstrated in-vitro in these studies indicated that seed extracts, independent of endophyte type can have deleterious effects on nematode viability.